Transient gene expression in shoot apical meristems of sugarbeet seedlings after particle bombardment

Sugarbeet apices were used as targets for particle bombardment with a microtargeting device. Before examining gene expression, particle penetration experiments were carried out. Transient GUS expression was detected within the first and second cell layers of the meristem. Dividing cells with GUS activity demonstrated that cells survived the bombardment procedur

Pojava embriona-blizanaca kod partenogenetske linije jare pšenice caudata-salmon

The twin-embryo formation in seeds of parthenogenetic wheat line caudata-Salmon (cS) after crossing to aestivum-Salmon (aS) was analyzed in this study. The basic hypothesis was that the frequency of twin-embryos was influenced by the developmental stage of cS spikes around the time of pollination. Spikes were separated into four developmental stages: the earliest - the apical part of spike emerged through the slit of the flag leaf sheath and the latest - 2-3 days after the whole spike emerged out of the flag leaf sheath. Twelve days after pollination seeds were opened under a stereo microscope with the aim to determine a frequency and dimensions of twin-embryos. Each twin-embryo consisted of one large and one small embryo. Dimensions of large twin-embryos were greater in spikes of later stages indicating the autonomous development of such embryos. Dimensions of small twin-embryos were similar in spikes of all stages indicating the zygotic development of such embryos. Established developmental pathways of twin-embryos agree well with the observation that the large germ in seeds of cS wheat line germinating with two germs is haploid while the smaller germ is diploid. The frequency of the twin-embryo was higher in spikes of later stages than in spikes of earlier stages. This can be explained by insufficient maturity of mother-cells of zygotic embryos. The embryo development via parthenogenesis in the embryo sac starts before the fertilization. According to the position of zygotic embryos, apart to the basal suspensor region of parthenogenetic embryos, the most probably they develop from fertilized sinergide.U ovom radu analizirana je pojava embriona-blizanaca u semenima partenogenetske linije caudata-Salmon (cS), dobijenim posle oprašivanja sa aestivum-Salmon linijom pšenice. Pošlo se od hipoteze da frekvencija embriona-blizanaca zavisi od stadijuma u kojima se nalaze klasovi u vreme oprašivanja. Klasovi su svrstani u četiri stadijuma, od pojave vrha klasa iz rukavca zastavičara do 2-3 dana posle izlaska celog klasa iz lisnog rukavca. Semena su 12 dana nakon oprašivanja otvorena kako bi se odredila frekvencija embriona-blizanaca i izmerile njihove dimenzije. Svaki od embriona-blizanaca sastojao se od jednog krupnijeg i jednog sitnijeg embriona. Dimenzije krupnijih embriona-blizanaca su bile veće u klasovima kasnijih stadijuma što je ukazivalo na njihov autonomni razvoj. Dimenzije sitnijih embriona-blizanaca su bile iste u klasovima različitih stadijuma, te je zaključeno da se radi o zigotnim embrionima. Ovo je u skladu sa opažanjima da je veća klica, kada seme cS linije klija sa dve klice, haploidna, a manja diploidna. Frekvencija embriona-blizanaca je bila niža u klasovima ranijih stadijuma. Ta pojava je objašnjena nedovoljnom zrelošću ćelija-majki zigotnih embriona. U embrionovoj kesici razvoj embriona partenogenetskim putem počinje pre nego što je postignuta fiziološka zrelost ćelije-majke zigotnog embriona. Na osnovu položaju zigotnih embriona zaključeno je da se oni najverovatnije razvijaju iz oplođenih sinergida

Introgression of apomixis into sexual species is inhibited by mentor effects and ploidy barriers in the Ranunculus auricomus complex

Background and Aims Apomictic plants maintain functional pollen, and via pollination the genetic factors controlling apomixis can be potentially transferred to congeneric sexual populations. In contrast, the sexual individuals do not fertilize apomictic plants which produce seeds without fertilization of the egg cells. This unidirectional introgressive hybridization is expected finally to replace sexuality by apomixis and is thought to be a causal factor for the wide geographical distribution of apomictic complexes. Nevertheless, this process may be inhibited by induced selfing (mentor effects) of otherwise self-incompatible sexual individuals. Here whether mentor effects or actual cross-fertilization takes place between diploid sexual and polyploid apomictic cytotypes in the Ranunculus auricomus complex was tested via experimental crosses. ¿ Methods Diploid sexual mother plants were pollinated with tetra- and hexaploid apomictic pollen donators by hand, and the amount of well-developed seed compared with aborted seed was evaluated. The reproductive pathways were assessed in the well-developed seed via flow cytometric seed screen (FCSS). ¿ Key Results The majority of seed was aborted; the well-developed seeds have resulted from both mentor effects and cross-fertilization at very low frequencies (1.3 and 1.6% of achenes, respectively). Pollination by 4x apomictic pollen plants results more frequently in cross-fertilization, whereas pollen from 6x plants more frequently induced mentor effects. ¿Conclusions It is concluded that introgression of apomixis into sexual populations is limited by ploidy barriers in the R. auricomus complex, and to a minor extent by mentor effects. In mixed populations, sexuality cannot be replaced by apomixis because the higher fertility of sexual populations still compensates the low frequencies of potential introgression of apomixi

A perspective on Hypericum perforatum Genetic transformation

Hypericum perforatum (St John's wort) is a reservoir of diverse classes of biologically active and high value secondary metabolites, which captured the interest of both researchers and the pharmaceutical industry alike. Several studies and clinical trials have shown that H. perforatum extracts possess an astounding array of pharmacological properties. These properties include antidepressant, anti-inflammatory, antiviral, anti-cancer, and antibacterial activities; and are largely attributed to the naphtodianthrones and xanthones found in the genus. Hence, improving their production via genetic manipulation is an important strategy. In spite of the presence of contemporary genome editing tools, genetic improvement of this genus remains challenging without robust transformation methods in place. In the recent past, we found that H. perforatum remains recalcitrant to Agrobacterium tumefaciens mediated transformation partly due to the induction of plant defense responses coming into play. However, H. perforatum transformation is possible via a non-biological method, biolistic bombardment. Some research groups have observed the induction of hairy roots in H. perforatum after Agrobacterium rhizogenes co-cultivation. In this review, we aim at updating the available methods for regeneration and transformation of H. perforatum. In addition, we also propose a brief perspective on certain novel strategies to improve transformation efficiency in order to meet the demands of the pharmaceutical industry via metabolic engineering.GF and PS are financed from the BIOTALENT project (GA621321) funded by the European Union Seventh Framework Programme (FP7) ERA Chairs Pilot Call and co-financed by funds allocated for education through project no W26/7.PR/2015 [GA 3413/7.PR/2015/2] for the years 2015-2019. This work was partially supported by Fundacao para a Ciencia e a Tecnologia (FCT) project (PTDC/AGR-GPL/119211/2010). WEE acknowledges the financial support provided by the FCT (SFRH/BD/52561/2014), under the Doctoral Programme "Agricultural Production Chains-from fork to farm" (PD/00122/2012).info:eu-repo/semantics/publishedVersio

Uticaj vremena primene auksina na formiranje haploidnih embriona pšenice

A hybrid interspecies zygote appears after crosses between wheat and maize Zygote derived after usual self-fertilization in wheat is dividing by mitotic divisions into embryo. However, interspecies zygote aborts soon. Auxin treatment is widely used to promote its development. Growth hormones auxins have stimulative ortoxic effects on plant tissue sin relation to its concentration and the time of application. In this paper the effect of time of auxin dicamba application on embryo in wheat x maize crosses was investigated. Chromosomes of pollen donor parent are eliminated quickly in cells of such embryos and they become haploid. It was concluded that for the production of haploid embryos the best time for auxin application is one day after pollination with maize.Posle ukrštanja pšenice sa kukuruzom nastaje hibridni interspecies zigot Zigot nastao uobičajenom samooplodnjom pšenice deli se mitotičkim deobama i formira embrion. Međutim, interspecies zigot relativno brzo abortira. Da bi se podstakao njegov razvoj koristi se auksinski tretman. Auksini su hormoni rasta koji u zavisnosti od koncentracije i vremena primene imaju stimulativni ili toksični efekat na razvoj biljnih tkiva. U ovom radu analiziranje efekat vremena primene auksina dikamba u koncentraciji od 100 ppm na formiranje embriona pšenice dobijenih posle ukrštanja sa kukuruzom. U ćelijama takvih embriona tokom razvoja brzo se gube hromozomi donora polena, te oni postaju haploidni embrioni. Zaključeno je da za proizvodnju haploidnih embriona optimalno vreme tretiranja klasova pšenice je jedan dan posle oprašivanja polenom kukuruza